2
“Planting” the Soil Moisture Sensor
It is important that the sensor is snugly planted. If you dig a large hole, the disturbed
soil will be less packed than the surrounding soil and will not accurately reflect its
condition. However, if the hole is too tight, the sensor can be damaged during
planting. Therefore, it is best to create a hole that matches the sensor’s dimensions
as closely as possible.
1. Make sensor access holes to the depth required with a 7/8”- 1” (2.2 - 2.5 cm)
diameter rod. (The ideal way to do this would be with a stepped tool with 2.5” of
7/8” diameter rod at the end of a 1.25” diameter rod. This would make an
oversize hole with an exact sized hole at the bottom where the sensor is located.)
Note:
For very coarse or gravely soils, an oversize hole of 1” to 1 1/4” may be needed to prevent
abrasion damage to the soil moisture sensor membrane. In this case, you will need to “grout in”
the sensor with a slurry made from the sample soil to get a snug fit in the soil. In gravelly soils and
with deeper sensors, use extra caution to install the sensor without damaging the membrane.
2. Always install sensors in the active root system of the crop with a snug fit in the
soil.
3. Fill the hole with water and push the sensor down into the hole so it bottoms out.
Tip:
A length of 1/2” Class 315 PVC pipe (pipe
inside diameter = 0.716”, 18.18mm) fits snugly
over the sensor collar and can be used to
push the sensor. You can solvent weld the 1/2”
Class 315 PVC pipe to the sensor collar for
easier installation and removal. Use a PVC/
ABS cement (IPS Weld-on #794 or
equivalent).
4. Carefully backfill the access hole with soil to eliminate any air pockets which
could allow water to channel down to the sensor.
Note:
Soil moisture sensors will provide better accuracy after one or two irrigation cycles, during which
time they “break-in” and acclimate to the soil conditions.
Sensor
Wires
Tape
1/2" Class 315 PVC P
(inside diamter = 0.71
18.18mm)
Pipe welded to
sensor collar with
PVC/ABS cement
Soil Moisture
Sensor